Groundwater Reliability Improvement Program through Indirect Potable Reuse
Hypothesis: An integrated nanofiltration/reverse osmosis (NF/RO) system will increase overall recovery to greater than 90% through operation of the NF membranes at higher fluxes, and recoveries at lower pressure.
The primary goals of the Groundwater Reliability Improvement Program (GRIP) are to:
1.Protect ground water quality and quality of life;
2. Provide a sustainable and reliable supply for replenishing the basins;
3. Minimize the environmental/energy footprint of any options selected;
4. Minimize costs to agencies using ground water
5. Engage stakeholders in a decisionmaking process.
Need and Benefit
Need: The greater Los Angeles (LA) basin is a microcosm of the 17 Western States that fall within the Bureau of Reclamation's authority. The area's water supply reliability is growing unpredictable due to continued population growth, local and regional droughts, climate change, and growing endangered species and environmental water needs. Tapping into alternative sources of water is becoming a necessity versus an option. One alternative has been implemented in Orange County. The Orange County Water District has demonstrated that advanced treated wastewater can be used to replenish ground water aquifers and withdrawn later for potable use. This method is referred to as indirect potable reuse (IPR). Recharge also benefits the ground water aquifer by reducing the potential for subsidence that results from overuse and by improving water quality related to salt and nutrient management.
This demonstration project proposal is a cooperative IPR-ground water recharge project between the Water Replenishment District of Southern California (WRD), the Upper San Gabriel Valley Metropolitan Water District (USGVMWD), and Los Angeles County Sanitation Districts (LACSD). These partners want to demonstrate the use of a NF/RO treatment process to treat up to 54.5 million gallons per day of effluent from the LACSD's San Jose Creek WRP. A NF/RO treatment process, if successfully demonstrated, would reduce the capital and operations/maintenance costs with a higher recovery rate compared to other existing treatment technologies. The product water (up to 46,000 acre-feet per year) would be used to recharge the Central and Main San Gabriel Groundwater Basins east and south of LA. These ground water basins are significant local supplies of water to several million people. Because of recent drought conditions, ground water basin levels have dropped to their lowest levels in recorded history. Without a ground water recharge program, both local supply reliability and water quality could become major issues.
Benefit: The demonstration project will assess the viability of a NF/RO process to treat wastewater effluent for IPR-ground water recharge. A concept was developed with NF as primary treatment to remove contaminants, followed by RO as a secondary treatment to further enhance the overall water recovery to over 93 percent. The NF provides the benefits of a high flux, low pressure (energy savings), reduced chemical usage, and provides a favorable water quality for additional recovery by the secondary RO system. If the treatment concept proves to be successful, the GRIP facility would have lower capital and operating costs than a conventional RO facility. In addition, the higher recovery would result
in substantially reduced waste discharge, as well as the associated brine disposal costs and increased local water supplies, and it would help to restore/maintain existing ground water aquifers.
The following documents were not reviewed. Statements made in these documents are those of the authors. The findings have not been verified.
GRIP - Evaluation of a high recovery NF-RO integrated treatment system (final report) (final, PDF,
By Dr. Bruce Mansell
Report completed on October 03, 2012